IHS says that there are roughly 252,700,000 vehicles in operation in the U.S. -- a high-water mark. (Keep in mind, that figure only includes light vehicles, not buses, big rigs, or other heavy duty commercial vehicles.) Since July 2013, 3.7 million vehicles have been added to the rolls, which translates to a 1.5 percent growth rate. The U.S. hasn't seen that kind of expansion since 2004-2005.

What's more, the number of vehicles that Americans are scrapping has tumbled. Roughly 11.5 million vehicles were sent to the crushers in 2013, well below the record high 14 million scrapped in 2012.

Given the huge number of cars on the road, the growth in registrations, and the diminishing number of vehicles being scrapped, it's no surprise that the average age of cars in operation is very high -- 11.4 years. That's the same as last year, though it's expected to increase to 11.5 years by 2017, and eventually it'll hit 11.7 years by 2019. (It would be growing faster, but today's strong new car sales are bringing down the average.)

Why is the average age of our vehicles increasing? IHS sees at least two major reasons:

Improved quality: Cars are built better than they once were. Increased regulation of the industry -- and, you could argue, the growing number of vehicle recalls -- mean that our cars are designed and managed to endure. As the mix of vehicles on the road slowly shifts to hybrid and electric models, the average age could skyrocket, since electric cars have no engines and thus, fewer moving parts, which means fewer opportunities for things to break.

Slower spending: The Great Recession made Americans more cautious about major expenditures, like buying cars. The old model of trading in a car after four years is going the way of the dodo, if it's not already gone. We're making do with what we've got for longer.

Is your car older or younger than the national average? Is its age causing you to think about something newer and shinier? Share your thoughts in the comments below.